Botanical Abstracts, 2(4): 115 (Oct 1919)

680. IKENO, S. On hybridization of some species of Salix. Jour. Genetics 8: 33-58. 1 pl. 1 fig. Dec., 1918.

Reference is made to Wichura's Salix hybrids breeding true in generations beyond F1. Experiments conducted with few species show this is not always the case with respect to certain characters. Growth habit of stem, pubescence of leaves, color of stigma, all show segregation in F2 but no definite Mendelian ratios were obtained. Stipulation of leaves is variable on F1 plants, some leaves with stipules, others without on the same plant, or even the two halves of the same stem may differ in this respect. Segregation of this character in F2 is not proved. Salix purpurea multinervis x S. gracilistyla gave two types of individuals with catkins resembling one or the other parent. When like F1 types of each of the two kinds were crossed together many of the same type of catkin and few of the opposite type were produced. When different types were mated approximate equality of the different types were secured in the offspring. In two of these matings a new type of catkin appeared. Both parents bred true for catkin type in one generation tested, 70 and 100 individuals having been grown. Several hypotheses are considered. Of these the most probable assures one or both of parents heterozygous for indivisible factors not affecting the catkin type in the parental combination in which they occur. Thus the appearance of the two types of catkins in F1 is not due to segregation of the main catkin factors themselves and all individuals in F1 agree in carrying these in heterozygous condition. Their segregation was found to take place in F2, the peculiar method of this segregation is explained on the basis of the subsidiary factors. The same cross repeated one year later between the same female individual and either the same individual male or from the same clonal line gave a different result in that no twin hybrids were produced but all the progeny (nearly 50 individuals) were of purely maternal type and all of the same sex. Literature on “false hybrids” (pseudogamy, merogony) is reviewed. Table of successful and unsuccessful hybridizations of various species of Salix is appended.—D. F. Jones.

See: Malinowski (Chromosome Affinity, Suppression of Characters, 1927)